In known devices, the body of the column generally consists of a section which has to be cut to a length compatible with the height of the ceiling; this measurement thus requires the manufacture of very long bodies and consequently causes the creation of considerable scrap metal.
Moreover, access to the point units is provided either by a cover which snaps on the body and, in this case, unauthorised staff can obtain access to live terminals, or by a hinged cover which it is difficult to make flat, because of its size, not to mention the difficulty of making a hinge which it is sought to conceal inside the body.